In order to achieve lateral support as well for telescopic booms, for example support against wind forces, guy supports that can not only be raised but can also be opened out into a V can be used. DE 100 22 658 A1 shows an appropriate telescopic boom in which the guy supports are pivoted on a swivel frame that is attached in such manner that it can swivel on top of the pivot section. The guy supports can be raised by swiveling the swivel frame. Additionally, the guy supports can be swiveled relative to the swivel frame so that they can be pressed open into a V. Here the guy supports are activated by means of an appropriate hydraulic cylinder. On the one hand, hydraulic cylinders are pivoted to the pivot section so as to raise the guy supports together with the swivel frame. On the other hand, hydraulic cylinders are pivoted to the swivel frame and the guy supports to adjust the angle of the guy supports relative to the swivel frame. This known arrangement makes it possible to adjust the angle opening of the guy supports independent of the raising of the guy support arrangement. On the other hand, however, it is cumbersome and its complicated construction makes it relatively expensive.
At their free projecting ends, the guy supports are connected with guy cables that run from the guy supports. When the telescopic boom is extended, and after appropriate raising of the guy supports, the guy cables are pulled out from the ends of the guy supports. With the boom in extended position, the guy cables fastened to the tip of the telescopic boom or also to the collar of one of the outward-telescoped section must be fastened at their support-side ends to the guy supports, with the guy supports in turn being held at the foot of the boom pivot unit. The guy cables can be supported on the guy supports by means of, for example, appropriate coils from which the guy cables run. However, because of the powerful forces, such coils must be of an appropriate size, and are therefore correspondingly heavy. Also, fastening the guy cables by means of cable clamps has already been proposed. However, it requires much effort to attach the cables in precisely the desired extended length. Additionally, there are objections with respect to long-term operating safety of such cable clamps.
It is therefore the task of the within invention to create an improved telescopic boom, of the type initially described, that avoids the disadvantages of the state of the art and improves on said state of the art in an advantageous manner. Preferably, a lightweight, simply constructed guy that permits simple, secure attachment of the guy cables in their desired extended length, as well as pre-stressing of the guy cables, should be created.
The task is performed according to the invention by a telescopic boom described herein. Preferred embodiments are also the subject herein;
According to the within invention, the extended guy cables can thus be positively engaged with the guy supports in their individual extended position. For this purpose, according to the invention, the guy cables have areas that are thickened, and the guy supports have appropriate cable locks that can be positively engaged with the thickened areas on the guy cables. The guy cables are thus attached to the guy supports not by means of an appropriate coil or a cable clamp mechanism, but rather by positive engagement by means of the said cable lock. By eliminating a cable coil for collecting the guy cable forces, the corresponding expensive and heavy coils and the heavy structure resulting therefrom can be avoided. Additionally, the problems of a cable clamp are eliminated. With the cable clamp the drawn-out cable lengths must be grasped precisely so that the cable will be clamped at the correct place. Another problem is the risk of build-up of dirt, so that the clamp effect changes with the change in friction coefficients during operation, whereupon a considerable potential danger can arise. In contrast, the solution of the cable lock according to the invention offers the advantage of ease of embodiment. At the same time the individual guy cable is gripped at precisely the designed length, which is predetermined by the permanently positioned thickened areas.
Preferably, the guy cable can be attached in several pre-determined lengths to the individual guy support. In a further development of the invention, each guy cable has thickened areas positioned at predetermined intervals, and the cable lock is designed in such manner that the individual guy cable with one or more thickened areas can run over the cable lock or can travel, with the individual thickened area, into the cable lock and can be locked there, as desired. To permit the individual thickened area to travel through or be attached to the cable lock, preferably the cable lock can have a mobile locking unit that can travel into and out of the path of the running cable. Preferably a swivel-locking piece that can swivel onto and can be swiveled away from the running guy cable can be provided. As activating device, preferably a pressure cylinder can be used, by means of which the locking piece of the cable lock can be swiveled appropriately.
The thickened areas can be designed in various ways. According to one advantageous embodiment of the invention, the thickened areas, which form radial projections on the cable, consist of clamping sleeves that are molded to the guy cable.
In guy cables with molded cable clamps or corresponding thickened areas, there is the problem that the guy cable cannot reasonably be wound on a drum. To assist with this problem, a cable pulley, positioned preferably inside the guy supports, into which the individual guy cable can be drawn, is used as a cable storage device, instead of a drum. Preferably the cable pulley has multiple channels, so that with the limited length of the individual guy support an adequate guy cable length can nevertheless be drawn in. In particular, several deflection pulleys can be positioned inside and at the ends of the guy supports, on which said deflection pulleys the guy cable is appropriately looped when the telescopic boom is readied for transportation and the guy cable is stowed away appropriately.
To permit the guy cable to be drawn through the individual cable pulley without problems, in a further development of the invention auxiliary cables are attached to the ends of the guy cables, which said auxiliary cables are drawn into the cable pulleys and can be wound on appropriate auxiliary coils. If the individual guy cable is to be drawn into the cable pulley, the auxiliary cable is wound on the auxiliary coil, so that the guy cable instead of the auxiliary cable is drawn into the cable pulley. Preferably, the auxiliary cable can have a considerably smaller diameter and/or with respect to its tensile strength can be weaker than the guy cable. The auxiliary cables are not used to collect the guy forces. These forces are collected by means of the aforementioned cable lock. When the guy cables are completely extended, the cables are no longer in the cable pulleys, into which only the individual auxiliary cable is drawn. The auxiliary coil for winding the individual auxiliary cable is preferably likewise positioned inside the guy supports.
Booms that are very long often bend, which is detrimental to the load-bearing capacity of the telescopic boom. When the boom bends, the force component acting in the longitudinal boom direction also receives a lever arm, so that the boom bends still further. It would therefore be very desirable to intercept and prevent bending already in the early stages by means of guy cables. However, this is difficult with the customary guy cables, since said cables cannot be sufficiently pre-stressed. To assist in this activity, according to another aspect of the within invention it is proposed to activate the cable lock by means of an actuator, in particular a hydraulic cylinder, in the longitudinal direction of the cable, and thereby to support the guy cable. A pre-stressing of the guy cable or cables can thereby be achieved, so that the bracing becomes effective already at a very early stage and the bending of the boom can be greatly reduced, particularly in the luffing of the tip. Lateral bending in particular can be clearly reduced by means of this new type of bracing. Accordingly, the column consisting of boom and, for example, luffing tip can be straightened or kept straight at a very early stage. By means of the hydraulic cylinder, considerable pre-stress can be placed on the guy cable. It is understood that the pre-stressing of the guy support by means of the cable lock actuator independent of the above-described positive locking between the cable lock and the thickened areas offers special advantages. If appropriate, the guy cable could also be designed without thickened areas and a frictionally engaged cable clamp can be provided as cable lock. In frictional-engagement locking as well, pre-stressing can be achieved by hydraulic-drive movement of the cable lock. However, the preferred form is the above-described positive engagement lock between the cable lock and the guy cable or the thickened positioned on the guy cable.
In another development of the invention, the cable lock is guided into a preferably corridor-type guide in such manner that the cable lock can be moved along a first adjustment path segment into engagement with or disengagement from the guy line, and when locked can be moved along a connecting second adjustment path segment in the longitudinal direction of the cable. The cable lock is thus initially moved crossways to the cable by means of a movement component and is locked. The locked cable lock is then led longitudinally along the cable in order to pre-stress the guy cable. To release the cable, the process is reversed. As soon as the cable lock reaches the guide in the first adjustment path segment, a movement component moves it away from the cable crossways to the cable.
In another development of the invention, the actuator hydraulic cylinder with its piston rod can be pivoted to swivel on the guy supports, and with its cylinder can carry the cable lock and can be led into the corridor-like guide. If the hydraulic cylinder is moved toward or away in relation to the piston rod, it follows the travel path predetermined by the guide. Theoretically it would of course also be possible to pivot the hydraulic cylinder to swivel on the guy supports and to guide the piston rod into the corridor-like guide. It would also be conceivable, instead of the corridor-like guide, to intercept the lateral swivel movement of the hydraulic cylinder by means of an additional actuator. However, the preferred embodiment is to pivot the piston rod and to attach the cable lock to the cylinder collar, from which the piston rod protrudes. In this way a particularly compact arrangement can be achieved.
To collect lateral forces as well, the guy supports can preferably be pressed open into a V, in which each of the guy supports can be housed to swivel on two separate swivel axes. Advantageously, each of the guy supports can be given just a single swivel cylinder, with the help of which the individual guy support can be swiveled if appropriate on its two swivel axes.
Advantageously, the guy supports have no inter-connections, that is, there are no anti-roll bars, lever mechanisms, etc., between the guy supports. The guy supports are pivoted to the boom lock at their boom ends only, and are connected with the pertinent swivel cylinder. This results in a particularly simple assembly of the guy support arrangement.